Melee Kills

I'm running strength stims, but also it caps at level 30 anyway so I don't think I even need those.

I'm using the TWG which has the highest damage and yet I'm still finding myself having to hit people 2-3 times in the head to get a kill, and sometimes I get what seems to be a lucky one hit kill.

Skill issue or is there something I'm missing? Do helmets reduce damage that much?

The range/animate does feel jank so it's entirely possible I just need to try more.